Multi-Giga Hertz (multi-GHz) sampling rate Digital to Analog Converters (DACs) are used to interface digital circuitry such as ASICs and FPGAs to analog circuits, for the purpose of digitally synthesizing arbitrary waveforms in applications.
Such applications can include wireless and wireline networks, digital terrestrial television, cellular communication, software defined radio, RADAR, and test and measurement applications.
In these applications, the use of high speed DACs with high dynamic range (accuracy) allows for direct digital synthesis of RF signals with none of the typical intermediate analog circuit functions, such as mixers and oscillators, resulting in systems with less distortion, fewer mixing products, and fewer spurious signals, leading to higher performance products.
Within a high-speed DAC, there are typically at least two types of circuitry: a digital portion and an analog portion. The digital portion encodes binary data for the following analog portion and also performs signal processing functions such as data scrambling, dynamic error matching, spur reduction coding, filtering, etc. The analog portion of the segmented DAC consists of precision matched analog circuits that convert the encoded data to analog currents or voltages.
Typical analog circuit non-idealities result in mismatches between unit slice output current pulses of: magnitude errors, timing offsets, and pulse width errors. These mismatches between the unit slices fundamentally limit the dynamic range (effective number of bits, SNR, etc.) of the DAC.
Against this background, the problem addressed by the present invention is to provide a conversion circuit, which overcomes the above mentioned problems.